Study On Shear Properties Of SnAgCu Micro-solder Joints

The development of new type SnAgCu series lead-free solder has becomeone of the main elements of research on electronic packaging new material. Butthe problems still exist in practical using about the welding spot is unreliable.This paper takes low-silver solder Sn0.3Ag0.7Cu and high-silver solderSn3.0Ag0.5Cu as its research objects and makes a comparison between the twowelding spots’ shearing law under the different diameters, loading rate, differentpads, and the different thickness of the IMC. Shear properties and effects of thecondition.Adopting various loading speed to shear mocro-solder joints tests, Researchresults show that both high-silver solder solder joints and in the low-silver soldersolder joints, shear strength increases with load rate. But low-silver solder solderjoints shearing strength increases with loading rate. And the shear strength hasthe trend of increasing which is very slow. As the shear-loading rates increase to acertain extent on shear strength of high-silver solder solder joints no longerincrease. In the same increase rates, Sn3.0Ag0.5Cu/Cu welding spot shearingstrength is greater than the Sn0.3Ag0.7Cu/Cu solder Sn3.0Ag0.5Cu/Cu.An exoperimental study and analysis was conducted under the condition ofdifferent diameter to Sn3.0Ag0.5Cu/Cu solder and Sn0.3Ag0.7Cu/Cu solder. Anddiscovered that there is obvious volume effect between the two solder jointsshearing strength and solder volume, as the weld diameter increases, the shearstrength reduces greatly; shearing strength increases, and spot size larger, solderjoints shear strength is much lower; but the greater the shearing strengthmagnitude was; in the same condition, high content of Ag solder joint shearstrength is always higher than the low content of Ag solder joint shear strength.After different time aging for shearing testing, we found the shear strengthof high-silver solder is higher than low silver solder. Comparing with thickness on Interfacial compound, high-silver solder thickness is always lower than thelow silver solder. To its interface compound, two solder joints were scallopshaped Cu6Sn5, basically no changes. As the aging time increases, shear strengthreduces along with, but shear strength of high-silver solder still has the trend ofcontinuing to reduce,and low silver solders has already got to be stabile.Finally, the paper discusses effects of aging the different pad of SAC305/Cuand SAC305/Ni solder pads (Cu and Ni) on the shear performance. There aredouble Ag3Sn and Cu6Sn5waves-Interfacial compound layer, while we onlyfound a layer of ingredients (CuNi)6Sn5compound of interface. Compared withcutting performance, Ni disk performance is better than Cu disk performance.